Bleaching wool grease



Patented Sept. 6, 1949 BLEACHIN G WOOL GREASE Eric R. Woodward, New York, and 1m Malnustrom. Brooklyn, N

Y., asslgnors to Mathlcson Chemical Corporation, a corporation of Virglnia No Drawing. Application January 80, 1941, Serial No. 725,270

5 Claims- (Cl. 260-4fi3) The present invention relates to the refining of wool grease and provides an improved method of effectin color improvement or bleaching of such material.

The characteristics and chemical composition of wool grease are materially different from those of other fatty materials of animal origin, and unusual difliculties arise in the refining of such grease. Wool grease consists primarily of a mixture of esters and alcohols. While wool greases vary somewhat as to composition, they usually contain about 14% of total cholesterol and also contain esters of cholesterol and alcohols of the fatty series including ceryl alcohol and alcohols with a smaller number of carbon atoms, also fatty acids including cerotic acid, palmitic acid, stearic acid and hydrostearic acid as well as resin acids and lanoceric anhydrides.

Wool greases readily absorb water and usually melt at a temperature of about 40 C. The socalled melting point of the crude as well as refined wool greases vary somewhat and is frequently an important factor in determining the suitability of a particular wool grease for a specific purpose.

It has previously been proposed to bleach wool grease by treatment with various chemicals including chlorine, sodium hypochlorite and hydrogen peroxide, or by treating the grease repeatedly at an elevated temperature with bleaching clay followed by subsequent treatment with decolorizing charcoal.

However, such methods have not been wholly satisfactory. For instance, the bleaching of wool greases with chlorine or hypochlorite has been found to lower the melting point of the resultant lanolin. Further, in the bleaching of wool grease by treatment with chlorine, the small amount of iron usuallypresent in the wool grease tends to form ferric chloride which imparts an objectionable red color to the lanolin. A disadvantage of the use of hydrogen peroxide for this purpose has been that it lowers the consistency of the lanolin. Also, many grades of crude wool grease cannot be satisfactorily bleached by the previously available methods.

In accordance with our present invention, the wool grease is effectively bleached by subjecting it to the conjoint action of sodium chlorite and sodium hypochlorite in the presence of water. In general, the process comprises admixing the hypochlorite in aqueous solution with the wool grease to be bleached and thereafter adding to the mixture an aqueous solution of sodium chlorite.

As previously noted, the treatment of wool grease with sodium hypochlorite alone has been .volving the use of sodium found deleteriously to affect the desirable properties of the wool grease. Further, sodium chlorite alone will not effectively bleach wool grease. We have found, however, that wool greases may be effectively and permanently bleached without deleteriously affecting their desirable characteristics by the conjoint use of sodium hypochlorite and sodium chlorite, provided the treatment is carried out substantially as herein described.

In carrying out our improved process, an acid condition of the reaction mixture is to be avoided. Otherwise, a permanent bleach ,is not effected. Substantially, colorimprovement has been effected under acid conditions but the color was found to be unstable, and within 24 hours or less the grease had materially darkened.

In accordance with our present invention, the pH of the reaction mixture may be either neutral or alkaline. Advantageously, a pH of 7 to about 11 has been used, but we prefer to maintain the pH of the reaction mixture above about 9,. say within the range of about 9 to 10. Also, in the conjoint use of sodium hypochlorite and sodium chlorite in the bleaching of wool greases, we have found that the order of the addition of the reactants is of major importance. This was a surprising discovery in view of similarmethods inchlorite in conjunction with sodium hypochlorite in the bleaching "of materials other than wool grease.

We have found that'if the chlorite is first added to the wool grease followed by the addition of the hypochlorite, or if the two are added to the grease concurrently, a satisfactory permanent bleach is not effected.

We cannot with certainty account for these peculiar results but we have found by repeated tests that where hypochlorite is first added to the wool grease, in accordance with our present invention, a satisfactory permanent bleach may be obtained, whereas if thereactants are added in any other order a permanent bleach is not obtained.

It presently appears that, in the absence of the hypochlorite, the chlorite reacts with the grease or some constituent thereof to form a product of an acidic nature, for in spite of the fact that the technical grade of chlorite used in carrying out this work contains some free caustic alkali, the pH of the mixture of the woo grease, chlorite and water has been found to be lower than would be expected from the acidity of the grease prior to the addition to the chlorite. However, where the hypochlorite is added prior to the addition of the chlorite, the pH of the resultant mixture is present disclosure. The

raised and is not substantially lowered by the subsequent addition of the chlorite.

While some color improvement may be effected where the chlorite is added prior to the addition of the hypochlorite, a satisfactory bleach is not obtained as the fat upon standing will materially darken.

In accordance with the present process, the hypochlorite and chlorite are added in aqueous solution to the wool grease in the specified order and thoroughly admixed with the wool grease by agitation, stirring for instance, or by blowing air into the mixture. To facilitate mixing, the wool grease should first be heated to a temperstare at which the grease is fluid. This temperature will vary with the particular grease being treated, but is usually below that at which substantial evolution of steam will occur.

The unique characteristic of the reaction between wool grease and the chlorite is emphasized by the fact that we have found that if the chlorite is added in a substantially dry form to the wool grease the batch will frequently catch fire, whereas a like addition of the chlorite to tallow, for instance, does not produce this result.

The proportions of sodium hypochlorite and sodium chlorite used in accordance with our present invention and also the ratios of the amounts of these materials may be varied somewhat depending upon the particular wool grease being treated and the extent of bleaching requiredx We have with particular advantage used about 1% of a technical grade of sodium chlorite, of 130% available chlorine, based on the weight of the wool grease. This proportion has with advantage been varied from about to about 5%. Larger proportions of chlorite may be used without injury to the grease but are not required.

A particularly desirable ratio of sodium hypochlorite to sodium chlorite has been found to be about 1:1 based on the available chlorine content of each. However, this ratio may be varied. Generally the ratio of hypochlorite to chlorite on an available chlorine basis should not exceed about 2:1. The minimum amount of hypochlorite used appears to depend primarily upon the acidity of a particular wool grease being treated. Wool grease the degree of acidity varies somewhat. We have found generally that at least suiflcient hypochlorite should be added to result in a mixture having a pH not lower than 7. A-more strongly acidic grease will require more hypochlorite than a less acidic grease, .but the amount of hypochlorite required for any particular wool grease may readily be determined in the light of the pH of the aqueous hypochlorite solution is about 10, and the pH of the wool grease-hypochlorite mixture may with advantage be brought into the desired range by the use of a greater or less amount of the hypochlorite.

The concentrations of the aqueous solutions of these reagents is not critical but suiilcient water should be used thoroughly to dissolve the respective reagents.

The pH of the resultant mixtures may be adjusted or maintained by conventional methods, for instance, by the addition of buffer salt. However, we have generally found that where the reagents are added, as herein specified, no special is acidic in nature andamples:

Example I A charge of 4,000 pounds of crude wool grease having an A. S. T. M. color of 6 was heated by steam in a lead-lined, open-top kettle and agitated with air. 430 pounds of sodium hypochlorite solution containing 12% available chlorine by weight, as sodium hypochlorite, was added and admixed with the grease. At this point in the operation the pH of the water layer was found to be 10.2. This addition of the sodium hypochlorite was immediately followed by the addition of pounds of a technical grade of sodium chlorite, of 130% available chlorine, and consequently' equivalent to 52 pounds of available chlorine, dissolved in about 400 pounds of water. After the addition of the chlorite the pH of the water washings of the resultant mixture was found to be 10.1. The heating and agitation was continued for about 1 hours after the addition of the chlorite, and at the end of this period the pH of the. water layer was found to be 9.6. During the operation the temperature of the batch was about 170 F.

Thereafter the wool grease was washed with water to remove extraneous salts and was subsequently freed from water in the conventional manner. The A. S. T. M. color of the batch so bleached was found to be 4 and the color was found to be stable over extended test periods.

Example I! layer after the additio 'of the hypochlorite was found to be 11, and after the addition of the chlorite the pH of the water washing was found to be 10.8. In this operation the final heating and agitation was extended to two hours and at the end of this period the wool grease was found to have an A. S. T. M. color of 3%, and the pH of the water washing was 9.6.

In each of the foregoing illustrations the color of the bleached wool grease was excellent and has been found to remain stable.

By the use of our present process we have been able to bleach satisfactorily grades of crude wool grease which could not be satisfactorily bleached by the previously known meth color improvement effected by ess has been found to compare the best bleach heretofore obtainable by treatment with hydrogen peroxide. However, as previously noted, the use of hydrogen peroxide for this purpose is subject to disadvantages including, in addition to those previously noted, a tendency toward the foaming over of the treating vessel. In accordance with our present in vention, such tendency is much less pronounced.

We claim:

1. A process for bleaching wool grease which comprises subjecting the wool grease to the conjoint action of sodium chlorite and sodium hypochlorite by mixing with the grease in a molten state an aqueous solution of sodium hypochlorite and immediately thereafter mixing with the resultant admixture an aqueous solution or sodium chlorite, the pH of the mixture to which the chlorite is added being non-acidic.

2. A process for the bleaching of wool grease which comprises subjecting the wool grease to the conjoint action of sodium chlorite and sodiumhypochlorite by mixing with the grease in a molten state an aqueous solution of sodium hypochlorite and immediately thereafter mixing with the resultant admixture an aqueous solution of sodium chlorite, the amount 01' hypochlorite added being at least sufiicient to neutralize the acidity oi the wool grease.

3. A process for bleaching wool grease which comprises subjecting the wool grease to the conjoint action of sodium chlorite and sodium hypochlorite by mixing with the grease in a molten state an aqueous solution of sodium hypochlorite and immediately thereafter mixing with the resultant admixture an aqueous solution of sodium chlorite, the pH of the resultant mixture being within the range of about 'I to 11.

4. A process for bleaching wool grease which comprises subjecting wool grease to the conjoint action of sodium chlorite and sodium hypochlorite by mixing with the grease in a molten state an aqueous solution of sodium hypochlorite and immediately thereafter mixing with the resultant admixture an aqueous solution of sodium chlorite, the amount of hypochlorite added being at least suflicient to neutralize the acidity of the wool grease and the proportion of hypochlorite to chlorite added being about equal on the basis of available chlorine.

5. A process ior bleaching wool grease which comprises subjecting the wool grease to the conjoint action of sodium chlorite and sodium hypochlorite by mixing with the grease in a molten state an aqueous solution of sodium hypochlorite and immediately thereafter mixing with the resultant admixture an aqueous solution of sodium chlorite, the proportion of sodium chlorite added being within the range of /2 to 5% based on the weight of thewool grease and the proportion of hypochlorite being about equal to the weight of the chlorite on the basis of available chlorine and at least suflicient to neutralize the acidity of the wool grease.

ERIC R. WOODWARD.

IVAR MALMS'IROM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,022,738 Reuter Dec. 3, 1935 2,129,719 Vincent Sept. 13, 1938 2,269,667

Kaufimann Jan. 13, 1942 OTHER REFERENCES 

